> This is a noticed side effect of trying to redo the function pointer > handling. This code: > > void *p1 = 0xdeadbeefdead0000, *p2 = 0xfeeddeadfeedbeef; > > probe_kernel_address(p1, p2); > > causes an immediate MCA and reboot on my HP zx2000 wherever I execute it > in the kernel. It's supposed to return -EFAULT. It isn't really safe to call probe_kernel_address() with any old garbage address on any architeture (e.g. if you pass it a memory mapped I/O address that has side effects when read ... you won't die, but you will mess up some future piece of I/O). That said ... ia64 does a particularly bad job with this. The reason is that the ia64 alt-dtlb miss handler assumes that all of region 6 (0xC...... & 0xD.....) and region 7 (0xE..... and 0xF.....) addresses map 1:1 with physical memory. Stray pointers in here result in TLB mappings being inserted for invalid physical addresses, which result in the MCA that you see. Fixing this would be hard ... validating the physical address in the alt-dtlb miss handler on the exceptionally sparse address space on some ia64 platforms would add significant costs. Perhaps ia64 could have its own real-function version of probe_kernel_address() that does a search of the EFI memory map ... this isn't used in any performance critical paths. -Tony -- To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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